See this Post
Try this ways :
using(SPSite oSite = new SPSite("https://server/site"))
{
using (SPWeb oWeb = oSite.OpenWeb())
{
SPListCollection docLibraryColl = oWeb.GetListsOfType(SPBaseType.DocumentLibrary);
foreach (SPList list in docLibraryColl)
{
Response.Write(list.Title+"<br>");
}
}
}
Hope its helps!!